Scale having a restrained movable balancing member

ABSTRACT

The balance beam of the scale is provided with a flexure member such as a spring at one end which serves to react against the pivoting force exerted on the beam at the opposite end. A transformer is also mounted on the end of the beam to emit a signal proportional to the displacement of the beam from a zeroposition. The flexure member is calibrated so that the signal of the transformer is proportioned to a measurement of weight of the mass being weighed on the scale.

[ Feb. 12, 1974 United States Patent [191 Swersey et al.

[ SCALE HAVING A RESTRAINED MOVABLE 2,668, 0 9 2,389,108 11 1945BALANCING MEMBER 177/210 X Yeager et al. 177/194 [76] Inventors: Burt L.Swersey, 313 W. Hartsdale Ave., Hartsdale, NY. 10530; Peter I. Fried 61Old Knollwood Rd., 1

White fi N Y 10607 Primary Exammer-George Hi Mlller, .lr.

Nov. 12, 1971 Attorney, Agent, or Firm-Kenyon & Kenyon Reilly Carr &Chapin 22 Filed:

21 Appl. No.: 198,133

Related US. Application Data ABSTRACT [63] Continuation-impart of Ser.No. 89,233, Nov. 13,

The balance beam of the scale is provided with a flex- 1970, abandoned.

ure member such as a spring at one end which serves to react against thepivoting force exerted on the beam at the opposite end. A transformer isalso mounted on the end of the beam to emit a signal proportional to thedisplacement of the beam from a zero-position. The flexure member iscalibrated so 44 4 W5 5 QQQJZ W I HZ Q 06 ,7 mtmn W7H 7 0 1 7 gl 7 .l. a5 7 m a 7 MW 1 7 u 31 n n n H 0C r. m w m M IL '0 C Cd S Ld U mF H UN 555 that the signal of the transformer is proportioned to a measurementof weight of the mass being weighed on the scale.

[56] References Cited UNITED STATES PATENTS 2,026,290 l2/l935Taraoka.......................... 177/234 X 32 Claims, 10 DrawingFigures SCALE HAVING A RESTRAINED MOVABLE BALANCING MEMBER Thisapplication is a continuation-in-part of copending application Ser. No.89,233 filed Nov. 13, 1970, now abandoned.

The invention relates to a scale. More particularly, this inventionrelates to a scale having a balance beam which is restrained in acalibrated manner during movement in response to a weight.

Heretofore, various scales have been known for measuring the weight of abody. For example, it has been known to utilize a hydraulic scale havinga load platform to receive a body and a hydraulic system which connectsthe load platform hydraulically to a balance beam so that the weight ofthe body can be transmitted as an unbalancing force onto the balancebeam. Such a scale further utilizes a movable counterweight which ismounted on the balance beam to restore the balance beam to an originalnull condition. In these instances, the distance the counterweight movesfrom its original position to the final balance position is used as ameasure of the weight of the body on the platform. These scales havegenerally been very accurate, for example, such scales have been knownto provide accuracy of from 0.02 percent to 0.005 percent of theweighing range. However, in the case where the final position of thecounterweight has been used as an indication of the weight of a body, ithas generally been necessary to move the counterweight manually. As aresult, in some applications of such scales, there has been anuneconomical use of time and labor. Further, in those cases where theamount of movement of the counterweight has been used as a measure ofthe weight, when the scales have been used to weigh over a relativelylarge range of loads, the time for the counterweight to travel from oneend of the load range to the other has been relatively long. As aresult, such scales can be inefficiently used in these circumstances.

Accordingly, it is an object of the invention to eliminate the need fora movable counterweight on a balance beam of a scale to balance out aload applied to the balance beam.

It is another'object of the invention to provide a hydraulic scale whichis sensitive to small increments of weight.

it is another object of the invention to provide a hydraulic scale whichis capable of a full scale readout in a minimum of time.

It is another object of the invention to draulic scale of componentdimensions.

It is another object of the invention to reduce the response time of ascale readout to a minimum of time.

It is another object of the invention to accurately measure weightswithin a relatively small tolerance range.

It is another object of the invention to provide a hydraulic scale whichis accurate to within 0.1 percent of a weighing range.

Briefly, the invention provides a scale which utilizes a restricteddisplacement of a member in response to an unbalancing force thereoncaused by a weighted load as a means for obtaining the weight of theload. The degree of displacement of the member is used as a measure ofthe unbalancing force and is calibrated so as to permit a directread-out of the weight of the load on a suitable read-out means.

provide a hy- The scale includes a load platform for receiving a body tobe weighed thereon, a member which is hydraulically connected to theload platform for displacement from a predetermined balanced or zeroposition in response to the placement of a body on the load platform, afirst means for proportionally restraining dis placement of the memberfrom the balanced position and a means for measuring a displacement ofthe mem ber from the balanced position as a measure of the weight of thebody on the load platform. This latter means includes one means formeasuring the amount of displacement and a read-out means for indicatinga weight proportional to the measured displacement so as to directlyread-out the weight of the load.

In one embodiment, the displaceable member is in the form of a balancebeam which is pivotally mounted on a fixed support while a hydraulicconnection is formed between the load platform and balance beam so as totransmit a force on the balance beam proportional to the load on theplatform. This force serves to unbalance the beam and pivot the samefrom the zero posi tion. In addition, the means for restraining thedisplacement of the balance beam is in the form of a flexure memberwhich is fixed at one end to the beam and at an opposite end to thefixed support. This flexure member, e.g., a coil spring, is calibratedso as to restrain the pivoting of the balance beam under the unbalancingforce imposed through the hydraulic connection to the load platform. Tothis end, the flexure member is mounted so as to be stretched duringpivoting of the beam. In this way, as the unbalancing force increases inmagnitude, the degree of stretch of the flexure member increasesproportionally thereto, in a linear relation.

The means for measuring the displacement of the movable member, i.e.,the balance beam, from the bal? anced position is provided adjacent theendof the balance beam to determine the amount of deflection of the beamupon pivoting under the unbalancing force of a load. In addition, themeasuring means and flexure member are calibrated with respect to eachother so that the elongation of the flexure member under load iscalibrated with respect to the measured amount of deflection for a givenposition of the flexure member relative to the fulcrum of the balancebeam. The measuring means is further interconnected with a suitablereadout device so that the amount of deflection can be transmitted tothe readout means, e.g., in the form of an electrical output signal, andtranslated into a readout indicative of the weight of the load on thescale.

The means for measuring the amount of deflection of the balance beam canbe of any suitable nature. For example, a linear variable difierentialtransformer coupled to a readout meter or other readout means by anelectronic circuit can be used. Further, any other optical, magnetic,mechanical, pneumatic, hydraulic or other suitable device canbe used totransmit a signal in correspondence to the amount of deflection of thebalance beam to a readout means for indicating the weight of the loadcausing the deflection of the balance beam.

In the embodiment where a linear variable differential transformer isused, the transformer functions to emit a signal, e.g., an AC millivoltsignal, in proportion to the amount of deflection of the balance beam toa digital volt meter as is known for purposes of a direct visualreadout. Alternatively, the AC signal of the transformer can beconverted to a DC signal, for example by demodulation, for transmissionto the digital readout means. Still further, the signal can be deliveredto a meter which includes a dial pointer which deflects from a zeropoint in correspondence to the strength of the signal supplied to themeter as well as a scale which indicates the magnitude of deflection.This scale can be sealed off directly in pounds or kilograms to indicatethe weight of the load on the load platform of the scale. In this way,slight deflections can be accurately detected and the weight of the loadcausing such deflections can be accurately measured.

It is noted that any suitable restraining means can be used to restrainthe pivoting motion of the balance beam. For example, it is possible toimpose a flow of air against the balance beam through a shutter device.This shutter device would be actuated by the amount of deflection of thebalance beam so as to increase the flow of air against the beam. Inaddition, depending upon the deflection of the beam, the means formeasuring the deflection of the beam would emit a signal in dependenceof the deflection so that the weight of the body can be accuratelymeasured.

It is to be noted that it is not necessary to return the balance beam tothe initial position in order to read out the weight of the load whichdisplaces the beam. Instead, the amount of deflection of the beam ismeasured so as to obtain an accurate measurement of the weight.

In another embodiment, the scale which utilizes a pivotable beam forweighing purposes is provided with a tare means of a constructionsimilar to the restraining means. Forexample, where the restrainingmeans is in the form of one or more springs, the tare means is also inthe form of a spring and is secured to the beam on an opposite side of afixed knife edge assembly forming the fulcrum of the beam. The tarespring functions in an opposite manner to the restraining spring, i.e.,when the restraining spring stretches, the tare spring compresses. Thepurpose of these tare. springs is to provide for an initial preload onthe beam where there is a light tare load. Should the tare load be aheavy load which provides a sufficient preload a less number of springsor no springs can be used. This also gives a greater sensitivity for thescale.

In the embodiment where a tare spring is used, the fixed knife edgeassembly can be positioned to the topside of the beam along with therestraining spring and tare spring. The load is applied on the undersideof the beam in this case. The advantage of this construction is that thedead weight of the beam itself is not applied to the totalizer knifeedge. Thus, the beam does not have to be preloaded through the totalizerto balance the moment introduced by the weight of the beam about thefixed knife edge. Instead, as the springs maintain the beam in contactwith the knife edge assembly through a minimal elongation of each, thehydraulic means for applying a load to the beam need only be incontiguous contact with thebeam without applying any load thereon. Ofcourse, a slight load may be applied to ensure contact. However, suchwould be insignificant relative to the gravity load of the loadplatform. It is further noted that the scale can be used toautomatically readout the weight of the load or to provide for a manualread out of the load. For example, in an automatic system, a signal froma transformer used in the deflection measuring means can be directed toa digital voltage meter which directly reads out the weight of the load.In the manual version, a null meter to null'or compensate for thevoltage is used instead of a digital volt meter along with twopotentiometers, i.e., pots, with one of the pots connected to the meterso as to adjust the meter initially to zero. Thereafter, when a load isplaced on the load platform of the scale, the pointer of the meter willdeflect. The second pot,'which can be a potentiometer provided with arotatably digitally calibrated knob or which can be precision coupled toa mechanical counter, is used to tare out the meter so as to bring thepointer back to the zero point while at the same time indicating theweight on the digital knob of the pot or on the counter.

The scale of the invention can further be provided with a temperaturecompensator so that all temperature inaccuracies of the scale can becompensated. To this end, a thermistor and a summer can be used forcalibration. In such a case, the thermistor changes in resistance inresponse to a change in temperature so that the signal from thedifferential transformer is compensated by the change in resistance soas to give a corrected signal for transmission to the digital volt meterof the readout means. Also, two temperature compensators can beprovided; one for' the hydraulic system so as to compensate fordifferences in temperature between the load platform load cells and thescale beam load cells and a second for the electronics of the system. Inthe event that a spring of predetermined spring constant is used torestrain the movement of the balance beam, such a spring is made of atemperature compensated material so that there is no zero creep due totemperature changes.

In addition, the scale can be provided with a digital printing voltmeterof known construction with a readout and a printer so that the weight ofthe body'can be directly printed onto a log which can be applied, e.g.,to a container in which a load of material is contained. The printer canalso be added as a separate unit to the scale.

The scale may also have a read out means which includes a suitable meansfor receiving and directing the signal of the transformer to a printeror computer in the form of a binary coded decimal signal so that theweight of a load can be directly printed out or processed by thecomputer.

In addition, instead of using a single flexure member,

- any number of springs can be used to restrain the pivoting motion ofthe balance beam of the scale. Also, in the event that the beam is tohave an increased or decreased working capacity, the position of theflexure member relative to the fulcrum of the balance beam can bechanged along with a recalibration of the sensitivity control or spancontrol of the digital volt meter.

These and other objects and advantages of the invention will become moreapparent from the following detailed description and appended claimstaken in conjunction with the accompanying drawings in which:

FIG. 1 illustrates a perspective view of a hydraulic scale constructedin accordance with the invention;

FIG. 2 illustrates aside view of the balance beam and support of FIG. 1;

FIG. 3 illustrates a view taken on line 3-3 of FIG. 2;

FIG. 4 illustrates an enlarged view of a load cell for imposing a forceon a common knife edge according to the invention;

FIG. 5 illustrates a fragmentary view of a linear variable differentialtransformer according to the invention;

FIG. 6 illustrates a block circuit diagram of the scale of FIG. 1;

FIG. 7 illustrates a schematic diagram of the scale of FIG. 1;

FIG. 8 schematically illustrates a modified scale according to theinvention utilizing a pneumatic restraining means;

FIG. 9 schematically illustrates a side view of a scale having a tarespring means according to the invention with a fixed knife edge assemblyon the topside of a balance beam; and FIG. 10 schematically illustratesa plan view of the scale of FIG. 9.

Referring to FIG. 1,.the scale 10 includes a load platform assembly 11for receiving a load thereon and a balance beam assembly 12 forindicating the weight of the load placed on the load platform assembly11.

The load platform assembly 11 is of any suitable construction andconsists, for example, of a loading or load platform 13 e.g.., ofrectangular shape mounted on a plurality of hydraulic load cells 14,each of which is placed at the corners of the plate form 13 and a bed 15which mounts the load cells 14 thereon. These respec tive load cells 14can be constructed in any suitable manner such as shown in US. Pat. No.3,338,323 or 3,530,949. The load platform assembly 11 is of relativelysmall height, e.g., 3 inches. In this way, the assem'blyll can bemounted directly on a floor so that heavy loads can be transported ontothe platform 13, for example, by a hand truck rolling up a ramp adjacentto the platform 13. Alternatively, the load platform assembly 11 can berecessed within a pit within a floor so that a load can be transporteddirectly onto the platform 13 without the need for a ramp.

Referring to FIGS. 1 and 2, the balance beam assembly 12 includes asupport bed 16 of channel shaped construction or any other suitableshape, a knife edge assembly 17 which is fixedly mounted to the supportbed, a balance beam 18 which is pivotally mounted on the knife edgeassembly 17 and a means 19 for imposing an unbalancing force on the beambalance 18. The knife edge assembly 17 (FIG. 3) includes a pair ofcolumn supports 20 which are vertically disposed and fixedly secured tothe support bed 16, and a U-shaped saddle 21 which is secured to thesupports 20. The saddle 21 is disposed transversely of the balance beam18 and carries a plurality of aligned knife edges 22 thereon whilesupporting a support plate 23 over the knife edges 22. The support plate23 is fixed, as by bolts 24, to the saddle 21 and supports a pluralityof hydraulic load cells 24 in depending manner therefrom.

Referring to FIG. 4, each load cell 24 includes a piston 25 which ismounted in an unguided manner within a housing 26 secured to the supportplate 23 and a flexible diaphragm 27 which is secured between thehousing 26 and the support plate 23 to lie in a normally flat conditionover a recess in the plate 23 in the projected plane of the piston 25.Alternatively, the load cells 25 can be constructed as in the abovementioned patents. The support plate 23 includes a suitable duct 28therein which communicates the surface of the plate 23 adjacent thediaphragm 23 with another surface so as to transmit a flow of hydraulicfluid thereto. In addition, the load cell 24 connects to a common knifeedge 29.

Referring to FIG. 1, the load platform assembly 11 is hydraulicallyconnected to the beam balance assembly 13 by way of suitable hydrauliclines 30 such that each line 30 connects a load cell 14 of the loadplatform ssembly 11 with a respective load cell 24 in the balance beamassembly 12. In this way, the hydraulic fluid within the lines 30communicates directly with the respective diaphragms 27 of the loadcells 24 on the opposite side of the piston. As a result, should a loadbe placed on the load platform 13, as the pressure in the hydrauliclines 30 increases, the respective diaphragms 27 lift from the supportplate 23 in the region of the ducts 28 so as to force the respectivepistons 25 outwardly from the housings 26. It is to be noted that eachpiston 25 is mounted within a housing 26 with a clearance so as to avoidfrictional drag thereon.

Each hydraulic line 30 which communicates with a corresponding duct 28within the support plate 23 is provided with a suitable valve assembly31 to permit adjustments in the volume of hydraulic fluid in the duct 28prior to use of the scale so as to set the pistons of the load cells 14at the proper height at the load platform 13.

Referring to FIG. 2, the balance beam 18 which is of an elongated lengthand narrow thickness carries an extension 32 at one end. This extension32 is in the form of a bar which extends parallel to the saddle 21 andincludes a pair of V-shaped notches 33, 34 therein. One notch 33 isformed in a lower surface of the extension 32 and is disposed over theknife edges 22 carried by the saddle 21 so as to establish a fulcrum forthe beam 18. The second notch 34 is formed in the upper surface of theextension 32 and receives the common knife edge 29 so that anunbalancing force due to a load W on the platform assembly 11 can beimposed on the balance beam 18. The extension 32 is secured to theremainder of the beam 18 by means of a pair of brackets 35 and suitablebolts 36. In addition, the extension 32 carries a plurality of shafts 37which extend away from the remainder of the balance beam 18 for mountingof counterweights 38 thereon.

Referring to FIGS. 1 and 2, the balance beam assembly 12 furtherincludes a flexure member 39 in the form of a single coil spring whichis fixedly secured at one end to the support bed 16 and at the oppositeend to the beam 18. To this end, the supportbed 16 is pro vided with anelongated channel shaped member 40 which defines an elongated recess 41and a plurality of apertures 42 which communicate across the recess 41for selectively receiving a pin 43. The pin 43 serves to anchor a hookedend (not shown) of the spring 39 with the recess 41 of the channelshaped member. In similar fashion, the balance beam 18 is provided witha bifurcated end having apertures 44 therein for receiving an' It is tobe noted that any suitable number of flexure members 39 can be securedbetween the support bed 16 and the balance beam 18 in order to restrainthe motion of the balance beam 18. Further, the balance beam 18 isprovided with a plurality of apertures 44 so as to permit the rod 45 foranchoring the spring 30 to be mounted in any one of a number ofpredetermined positions. In a similar manner, the support bed 16 isprovided with suitable threaded openings so as to permit the elongatedchannel shaped member 40 to be secured in different positions along thesupport bed 16 relative to the openings in the balance beam 18. In thisway, depending upon the forces which are to be weighed on the loadplatform, the position of the flexure member can be changed toaccommodate such load ranges.

Referring to FIGS. 1 and 5, the balance beam assembly 12 also includes alinear variable differential transformer 47 which is mounted near oneend of the balance beam 18. This transformer 47 includes a coil 48 whichis fixedly mounted on a suitable bracket 49 fixed to the support bed 16and a'core 50 which is fixedly mounted on a bracket 51 fixed to thebalance beam 18. The core 50 is disposed in a vertical plane andcooperates with the coil 48 so as to produce an electrical AC outputsignal when the core 50 is moved within the coil 48 during displacementof the beam 18. As shown in FIG. 1, the coil 48 of the transformer 47 iselectrically connected to a suitable control box 52 including ademodulator so that the output signal can be converted into a DC signalor a linear phase detector so that the phase of the AC signal can bedetected. The control box 52, in turn, is electrically connected to adigital readout means 53 so that the weight of the load can be read outdirectly in relation to the signal received in the read out means.

Alternatively, the read. out means can include a meter 54 having a scale55 and a movable pointer 56 thereon which indicates the strength anddirection of the output signal. This meter 54 can be calibrated to readout directly in pounds or kilograms for small deviations. Also, themeter 54 can be connected electrically to a digital readout (not shown),such as a printer, which receives a signal from the meter 54 so as todigitally indicate the value corresponding to the strength of the signalreceived in the meter 54.

In addition, a digital precision potentiometer 57 is connected to thecontrol box 52 so as to permit the voltage signal received therein to betared out so that the reading on the readout means 53, 54 can bereturned to a zero position should a preload on the spring 37 cause thetransformer 47 to emit an output signal. Also, the zero position can beobtained electronically by incorporation of suitable circuitry which isoperated by a push button.

In operation, the hydraulic scale is first balanced so that the pistonsof the load cells 14 are in a first position. At this time, the balancebeam 18 is positioned in a generally hroizontal plane while the coilspring 39 is in a slightly stretched condition so as to provide a veryslight preload on the balance beam 18. At the same time, the digitalread out 53 registers zero. In the event that the digital readout 53does not indicate a zero digit, the potentiometer 57 can be manuallyadjusted so as to bring the readout 53 to the zero position. A load W isthen placed on the load platform 13. As a result, the hydraulic pressurewithin the load cells 14 under load platform 13 transmit a pressurethrough the hydraulic lines 30 into the load cells 24 of the balancebeam assembly 12. In order to reduce the load applied to the pistons 25the respective sets of load cells 14, 24 are dimensioned, for example,on a four to one basis so that the load transmitted to the balance beamassembly 12 is proportional to the load W on the platform 13. As thepressure in the load cell 24 in the balance beam assembly 12 increases,the knife edge 29 is moved in a downward direction causing the balancebeam 18 to pivot about the fulcrum. At the same time, the flexure member30 restrains the pivoting movement of the balance beam 18 in acalibrated manner. However, the balance beam 18 will deflect upwardlyfrom the balanced position causing the core 50 of the transformer 47 tomove relative to the coil 48 and causing an electrical signal inmillivolts to be transmitted to the control box 52. The signal is thentransmitted to the digital readout 52 so that a value proportional tothe electrical signal and equal to the actual weight of a load W on aload platform 13 is readout.

The centerline of action of the flexure member 39 is precisely locatedwith respect to the fulcrum of the balance beam 18. In this way, aprecise proportional restraining force can be imposed on the balancebeam 18 during a weighing operation in opposition to the unbalancingforce imposed on the balance beam 18 by the hydraulic fluid of thehydraulic system. Consequently, the amount of deflection of the balancebeam 18 gives a proportional indication of the true weight of the load Won the load platform 13. This deflection (which can amount to 0.040inches maximum), is accurately detected by the transformer 47 and asignal proportional to the deflection is emitted to the control box 52which translates the signal to an accurate digital readout in the readout means 53. As a result, the readoutaccurately indicates the actualweight of the load W on the load platform 13 during a weighingoperation.

It is further noted that a scale constructed in accordance with thisinvention provides an accurate readout out of 0.1 percent or better ofthe weighing range of the scale, i.e., one part in one thousand. Inaddition, the response time of the scale can be varied within anysuitable range, such as from 0.2 seconds to 3 seconds.

It is further noted that the core 50 of the transformer 47 is located ina vertical plane. However, the deflection of the balance beam 18 fromthe balanced position either upwardly or downwardly is generally oflimited amount such that the core 50 does not deflect from a verticalposition to any significant degree. This core 50 can also be mounted ina manner so as to. compensate for variations in beam movement due totemperature. For example, the core 50 can be mounted on a bimetallicbracket 51 which causes the core 50 to move in a direction to compensatefor temperature induced movements in the remainder of the scale.

It is further noted that the scale can be initially tared out so as tocompensate for an initial preload on a load platform 13. For example,should any empty container be placed on the load platform 13, anelectrical signal will be emitted by the transformer 47 and the digitalreadout 53 will indicate the weight of the container. Thereafter, thepot 57 is adjusted, e.g., manually, to balance out the electrical signalfrom the transformer 47 such that the signal readout 53 will have a zeroscale reading. Thereafter, the material to be weighed can be depositedinto the container on the load platform. The balance beam 18 will thendeflect to a greater amount so that the signal from the transformer 47will increase in intensity and produce a reading on the readout 53. Thereading of the digital readout 53 will then be an accurate reading ofthe weight of the contents of the container.

It is also noted that the digital readout can be in the form of adigital volt meter which gives negative and positive values. Such areadout can be used to determine deviations in weight from a standardweight of prefilled containers. in such a case, the zero point of thereadout would indicate the standard full load. The readout could alsouse the zero point to indicate a no load position.

It is further noted that if a variable load is to be placed on the loadplatform 13 that the scale 10 which uses the volt meter 54 in thereadout means not only will indicate the actual weights of the varyingload but also the meter 54 will indicate whether the weight isdecreasing or increasing since the pointer 56 of the meter 54 willdeflect about the zero point of the scale 55 thereon in accordance withthe directional output signal received from the transformer 47. In thisway, the scale can be used in various types of batching operationswherein a load of material is poured into a container which has beenpreviously mounted on the load platform. I

' Depending upon the load to be placed on the load platform 13, theposition of the flexure member 39 can be adjusted longitudinally of thebalance beam 18. That is, where the range of loadings are to be ofrelatively small weights, the flexure member 39 can be positioned closerto the fulcrum. n the other hand, where the range is for relativelylarge weights, then the flexure member 39 is positioned at the farthestposition from the fulcrum. In addition, more than one flexure member canbe used on the scale such that the capacity of the scale can be furtherincreased. In any of these cases, the proportional constants, such as,the spring constants of the flexure members, are calibrated with respectto the signals which are emitted by the transformer 47 by a suitablecontrol within the digital readout so that accurate readings can begiven for different positions of the flexure member with respect to thefulcrum of the balance beam 18. In this respect, for a given constantweight, the closer the flexure member 39 is brought to the fulcrum ofthe balance beam 18, the greater will the deflection of the balance beambe from the balanced position. As a result, the strength of the signalfrom the transformer 47 will increase. In order to compensate for thisincrease signal, the digital readout 53 is proportionally adjusted toindicate the correct weight of the load on the load platform.

It is further noted that the balance beam assembly 12 of the scale 10can be located a substantial distance from the load platform assembly11. In this way, the balance beam assembly 12 can be isolated fromsurrounding environmental conditions so as to be uneffected thereby. Forexample, the balance beam assembly 12 can be enclosed within a housing(not shown) which is maintained at a constant temperature and humiditysuch that fluctuations due to these parameters will not be introducedinto the operation of the scale 10. Alternatively, the balance beamassembly 12 can also be provided with a suitable temperature compensatorin order to compensate for variations in temperature. To this end, athermistor can be utilized for calibration. In such a case, alltemperature inaccuracies can be summed together in the thermistor sothat the absolute value of the temperature variation can be obtained forcorrecting the signal from the transformer 47.

The scale can also be modified to utilize two digital volt meters. Inthis instance, one digital volt meter can be used to measure the grossand net weight of the load on a load platform while the second meter isused to measure only the net weight of the contents of the container orfluctuations in weight of a variable-load on the load platform.

The scale of the invention can also be constructed so as to utilize amanual control. In this case, the scale would use a DC amp meter insteadof a digital volt meter as above and two pots. One pot would be utilizedto bring the amp meter to a zero reading before a load is supplied tothe load platform in order to balance out any signal emitted by thetransformer due to the deflection of the beam from the balanced positionthereof. Thereafter, a load would be mounted on the load platform andthe amp meter would read out a signal in proportional correspondencetherewith. The second digital pot would then be coupled with the ampmeter and would be manually adjusted as by a calibrated knob or a knobconnected to a counter so as to compensate the reading on the meter.That is, the second pot would bring the pointer of the amp meter back toa zero reading while at the same time the calibrated knob or counter iscaused to indicate the weight of the load on the load platform as themeter reading is decreased. Alternatively, the amp meter can becalibrated for a direct readout of small deviations of the balance beam.

Referring to FIG. 6, a block diagram of the electrical circuitry betweenthe transformer, digital volt meter and potential are shown. It is notbelieved that any further description of the block diagram is required.

Referring to FIG. 7, a schematic diagram of the electrical circuit ofthe scale is shown and no further de scription is believed to benecessary.

Referring to FIG. 8, wherein like reference characters indicate likeparts as above, the scale can alternatively be constructed such that therestrain on the beam 18 is imposed by a jet of air. In such a case,instead of using a flexure member as above, a suitable pneumaticassembly 60 is positioned adjacent to the balance beam 18 so as to causea jet of air 61 to impinge upon the balance beam 18 in counterbalance tothe application of the load from the hydraulic system. In addition, theforce of the jet of air 61 on the balance beam 18 is variedproportionally in the manner of a linear spring to the amount ofdeflection of the beam 18. That is, as the beam 18 increases in anupward deflection as viewed towards the source of the air jet, the forceof the air jet is increased. For example, the velocity head of the airjetis increased by narrowing the jet of air by means of a shutter (notshown) at the orifice 62 of the pneumatic system 60 through which theair jet is expelled. This shutter is controlled in relation to theamount of deflection of the beam 18 as sensed by a transformer 47 asabove, positioned adjacent to the balance beam 18. The signal which isemitted by the transformer 47 is transmitted, as above, through acontrol box 52 and readout 53 as well as directly to the shutter suchthat as the amount of deflection increases, the signal increases andcauses the shutter toclose. The calibration of the shutter is such as toproportionally change the force of the air jet on the balance beam 18 ina manner similar to the member described above.

' The pneumatic system 60, as above, can be movably mounted in any oneof a number of predetermined positions along the balance beam 18 in anysuitable manner.

It is noted that the balance beam assembly can be oriented in theposition as shown or in a position turned 180 over on itself.

Referring to FIGS. 9 and 10, wherein like reference characters indicatelike parts as above, the fixed knife edge assembly 17 is mounted to havethe knife edge or edges 22 abut the extension 32 of the balance beam 18on the topside. Also, the means 19 for imposing a load is mounted on theunderside of the beam 18 to have the knife edge 29 abut the extension32'. In addition, an

end restraint 7(1) is secured on each side surface of the estension 32to prevent lateral slippage of the respective knife edges 22, 29.

The restraining means includes a plurality of coil springs, 39 or thelike arranged in two rows of six springs. Each spring 39 is secured atone end to a pin 71 which, in turn, is mounted in a channel shapedholder 72 secured to aside wall of the beam 18. The

' opposite end of each spring 39 is secured in a housing 73 mounted onand extending across the support bed.

.As above, a linear variable differential transformer (not shown) ismounted at the end of the beam 18 on a bracket 49. Also, a restraintblock 74 is secured to the end of the beam 18 to project into arestraint assembly 75 so that a limit control is imposed on the amountof movement of the beam 18. The restraint assembly 75 is adjustable asshown.

Additionally, a tare means 76 is mounted to an opposite side of theknife edge assembly 17 from the coil springs 39. This tare means 76includes a single row of six coil springs 77 each of which is fixed to apin 78 mounted in a channel shaped holder 79 which is, in turn, securedto the beam 18. The upper end of each spring 77 is secured over anadjusting screw 80 so as to be elongated under tension upon turning ofthe screw 80. To this end, each screw 80 is threaded into a fixedhousing 81 extending above and across the bed 16.

The knife edges 29 of the totalising means 19 are positioned to abut theextension 32' and impose a slight,

I if any, force thereon when the beam 17 is in a level zero or nullposition. To this end, the height of the knife edges 29 can be madeadjustable in any suitable manner. Thus, the springs 39, 77 serve tosupport the dead weight of the beam 17 and connected components whileelongating slightly. This elongation can be calibrated into the scaleduring manufacture or when in use. Further, adjustment of the beam 17can beeasily carried out via the adjusting screws 80.

As the beam is free of gravity imposed loads, the beam can be orientedin any suitable position including a vertical position. The scaleotherwise operates as described above.

In order to operate the system while incurring vibration or whilewithstanding shock loadings, suitable valves are provided in thehydraulic lines to the totalizer which provide a variable orifice. Byvarying the valve openings, any wave action in the hydraulic fluid 6resisting side loads which may be imposed on a load platform or the loadcells in view of the vibration damping characteristics thereof.

It is further noted that the scale of the invention can be used with aprinting system in which the signals emitted by the digital readout canbe used for printing of corresponding values on a log sheet. In such acase, a printing digital volt meter as is known can be used for thereadout and printing. Alternatively, the printer can be a separate unitfrom the readout.

Further, the readout device can also be constructed as a potentiometerto receive a voltage signal from the control box via a voltmeter, asdescribed above. In this case, the potentiometer is constructed so as tobalance out the received voltage by applying a reverse or negativevoltage thereto. By this functioning as a null meter, the amount ofnegative voltage applied is used to digitally indicate the weight of aload being weighed.

It is noted that instead of using a load platform per se to receive aload to be weighed, a single load cell can be used to receive the load.Also, one .or more load cells can be connected, e.g., to the base of atank which is to receive a charge of material to be weighed.

The invention thus provides a scale which is accurate to a significantdegree and which can be used for various industrial purposes. Inaddition, the scale is of compact construction suchthat the balance beamassembly can be isolated from the loading platform and the envi ronmentsurrounding the loading platform.

The invention further provides a scale which is precise and which can beconstructed in an economic manner. In this respect, it is noted that thehydraulic system of the scale prevents the occurrence of any vibrationalproblems which would otherwise effect the precision of the scale.

The invention further provides a scale which can operate in spite ofvibrations, shock loadings or side load variations with extremeaccuracy.

What is claimed is:

l. A scale comprising a balance beam;

a support pivotallymounting said balance beam thereon in a firstposition;

means for imposing an unbalancing force on said balance beamproportional to a load to be weighed for pivoting said balance beam onsaid support from said first position, said means including a load platform for receiving a body to be weighed and a hydraulic means fortransmitting a force proportional to the weight of a body on said loadplatform to said balance beam;

first means fixedly secured to said beam and to said support forproportionally restraining the pivoting of said balance beam under animposed unbalancing force; and

means spaced from and calibrated to said first means for measuring adisplacement of said balance beam from said first position as acalibrated measure of the unbalancing force on said balance beam.

2. A scale as set forth in claim 1 wherein said hydraulic means includesa first plurality of hydraulic load cells supporting said load platform,a second plurality of hydraulic load cells hydraulically connected tosaid first plurality of load cells in spaced relation, and a knife edgeconnected in common to said second plurality of load cells for imposingthe unbalancing force onto said balance beam.

3. A scale as set forth in claim 1 further comprising tare spring meanssecured to said beam for restraining the pivoting of said beam, andwherein said support abuts the topside of said balance beam.

4. A scale as set forth in claim 1 wherein said means for proportionallyrestraining the pivoting of said balance beam is adjustably mounted atpredetermined positions longitudinally of said support and said balancebeam.

5. A scale as set forth in claim 1 wherein said means for proportionallyrestraining the pivoting of said balance beam is a flexure member fixedat one end to said support and at an opposite end to said balance beam.

6. A scale as set forth in claim 5 wherein said flexure member ismounted on one side of said support and said means for imposing anunbalancing force is mounted on an opposite side of said support.

7. A scale as set forth in claim 1 wherein said means for proportionallyrestraining the pivoting of said balance beam includes at least one rowof coil springs.

8. A scale as set forth in claim 7 further including at least one tarespring on an opposite side of said support for restraining pivoting ofsaid beam, said tare spring functioning in an opposite sense to saidcoil springs.

9. A scale as set forth in claim 1 wherein said means for measuring adisplacement of said balance beam includes a linear variabledifferential transformer for sensing the displacement of said balancebeam and emitting an electrical output signal directly proportional tothe displacement and a read-out means connected to said transformer toreceive said output signal and to digitally indicate the weight of theload causing said unbalancing force on said balance beam in proportionalresponse to said output signal.

10. A scale as set forth in claim 9 wherein said readout means is adigital read out.

1.1.A scale as set forth in claim 9 wherein said readout means is a DCamp meter calibrated to directly read-out the weight of the load.

12. A scale as set forth in claim 9 wherein said readout means includesa volt meter connected to said transformer to receive said output signaland to indicate the voltage strength and direction of said outputsignal.

13. A scale as set forth in claim 12 wherein said readout means furtherincludes a first precision digital potentiometer connected to saidtransformer for adjusting said meter to a zero equilibrium positioncorresponding to the balanced position of said balance beam whereby saidmeter can be tared out before an unbalancing force is applied to saidbalance beam.

14. A scale as set forth in claim 13 which further includes a seconddigital volt meter connected to said transformer to receive said outputsignal and a second read-out means connected to said second digital voltmeter to receive a signal therefrom; said second volt meter beingadjustable to tare out a first output signal whereby subsequent outputsignals from said transformer are transmitted to said second read-outmeans to provide measured values of net weight of a variable unbalancingforce.

15. A hydraulic scale as set forth in claim 13 wherein said read-outmeans further includes a second precision digital pot connected to saidtransformer and said meter for adjusting said meter to said zeroequilibrium position with said balance beam displaced from said balanceposition whereby said meter can be tared out with said second potindicating the weight of the load.

16. A hydraulic scale comprising a load platform for receiving a body tobe weighed thereon; I

a balance beam;

a support pivotally mounting said balance beam thereon in a balancedposition;

hydraulic means for transmitting a force proportional to the weight of abody on said load platform to said balance beam to pivotally displacesaid balance beam from said balanced position;

first means for proportionally restraining the displacement of saidbalance beam from said position;

second means for measuring a displacement of said balance beam from saidposition; and

read-out means connected to said second means for indicating a weightproportional to a measured displacement of said balance beam whereby theweight of the body on said load platform is indicated.

17. A hydraulic scale as set forth in claim l6 wherein said loadplatformis spaced from said balance beam and said support.

l8. Ahydraulic scale as set forth in claim 16 wherein said first meansis a flexure member.

19. A hydraulic scale as set forth in claim 16 further comprising a tarespring means connected between said support and said beam to restrainpivoting thereof.

20. A hydraulic scale as set forth in claim 19 wherein said supportabuts said beam on the topside between said tare spring means and saidfirst means.

21. A hydraulic scale comprising a load platform for receiving a body tobe weighed thereon;

a member hydraulically connected to said load platform for displacementfrom a predetermined position in response to the placement of a body onsaid load platform and movement of said load platform;

first means for proportionally restraining displacement of said memberfrom said first position;

second means for measuring a displacement of said.

member from said first position; and

read-out means connected to said second means for indicating a weightproportional to a measured displacement of said member whereby theweight of the body on said load platform is. indicated.

22. A hydraulic scale as set forth in claim 21 wherein said member is apivotally mounted balance beam.

23. A hydraulic scale as set forth in claim 21 further comprising a tarespring means connected between said load platform and said'm'ember forrestraining movement of said member.

24. A hydraulic scale as set forth in claim 21 wherein said first meansincludes a flexure member secured at one end to said balance beam and atan opposite end to a fixedly mounted support.

25. A hydraulic scale as set forth in claim 24 wherein said flexuremember is adjustably mounted longitudinally of said balance beam.

26. A hydraulic scale comprising a load platform for'rceiving a body tobe weighed thereon;

a balance beam; I

a support pivotally mounting said balance beam thereon in a balancedposition;

hydraulic means for transmitting a force proportional to the weight of abody on said load platform to said balance beam to pivotally displacesaid balance beam from said balanced position; first means forproportionally restraining the displacement of said balance beam fromsaid position;

an electrical means-spaced from said first means for measuring adisplacement of said balance beam from said position; and

read-out means connected to said electrical means for indicating aweight proportional to a measured displacement of said balance beamwhereby the weight of the body on said load platform is indicated.

27. A hydraulic scale as set forth in claim 26 wherein said electricalmeans is calibrated with respect to said first means.

28. A hydraulic scale as set forth in claim 26 wherein said first meansis a flexure member and wherein said flexure member and said electricalmeans are calibrated with respect to each other whereby the elongationof said flexure member under load is calibrated with respect to themeasured amount of deflection for a given position of said flexuremember relative to a fulcrum of said balance beam.

29. A scale comprising a balance beam;

a support pivotally mounting said balance beam thereon in a firstposition; i means for imposing an unbalancing force on said balance beamproportional to a load to be weighed for pivoting said balance beam onsaid support from said first position; first means for proportionallyrestraining the pivoting of said balance beam under an imposedunbalancing force;

means spaced from said first means for measuring a displacement of saidbalance beam from said first position as a measure of the unbalancingforce on said balance beam; and

tare spring means secured to said beam for restraining the pivoting ofsaid beam, and wherein said support abuts the topside of said balancebeam.

30. A scale comprising a balance beam;

a support pivotally mounting said balance beam thereon in a firstposition;

means for imposing an unbalancing force on said balance beamproportional to a load to be weighed for pivoting said balance beam onsaid support from said first position; first means for proportionallyrestraining the pivoting of said balance beam under an imposedunbalancing force; and

means spaced from said first means for measuring a displacement of saidbalance beam from said first position as a measure of the unbalancingforce on said balance beam, said means for measuring a displacement ofsaid balance beam including a linear variable differential transformerfor sensing the displacement of said balance beam and emitting anelectrical out-put signal directly proportional to the displacement anda readout means connected to said transformer to receive said outputsignal and to digitally indicate the weight of the load causing saidunbalancing force on said balance beam in proportional response to saidoutput signal.

31. A hydraulic scale comprising a load platform for receiving a body tobe weighed thereon;

a balance beam;

a support pivotally mounting said balance beam thereon in a balancedposition and abutting said beam on the topside thereof;

hydraulic means for transmitting a force proportional to the weight of abody on said load platform to said balance beam to pivotally displacesaid balance beam from said balanced position;

first means on one side of said support for proportionallyrestrainingthe displacement of said balance beam from said position;

second means spaced from said first means for measuring a displacementof said balance beam from said balanced position;

read-out means connected to said second means for indicating a weightproportional to a measureddisplacement of said balance beam whereby theweight of the body on said load platform is indicated; and I a tarespring means connected between said support and said beam on an oppositeside of said support from said first means to restrain pivoting of saidbeam.

32. A hydraulic scale comprising a load platform for receiving a body tobe weighed thereon;

a member hydraulically connected to said load platform for displacementfrom a predetermined position in response to the placement of a body onsaid load'platform and movement of said load platform;

first means for proportionally restraining displacement of said memberfrom said position, said first means including a pneumatic system forimpinging a jet of air on said member, the force of said jet air beingproportional to the displacement of said member;

second means for measuring. a displacement of said member from saidposition; and

read-out means connected to said second means for indicating a weightproportional to a measured displacement of said member whereby theweight of the body on said load platform is indicated.

1. A scale comprising a balance beam; a support pivotally mounting saidbalance beam thereon in a first position; means for imposing anunbalancing force on said balance beam proportional to a load to beweighed for pivoting said balance beam on said support from said firstposition, said means including a load platform for receiving a body tobe weighed and a hydraulic means for transmitting a force proportionalto the weight of a body on said load platform to said balance beam;first means fixedly secured to said beam and to said support forproportionally restraining the pivoting of said balance beam under animposed unbalancing force; and means spaced from and calibrated to saidfirst means for measuring a displacement of said balance beam from saidfirst position as a calibrated measure of the unbalancing force on saidbalance beam.
 2. A scale as set forth in claim 1 wherein said hydraulicmeans includes a first plurality of hydraulic load cells supporting saidload platform, a second plurality of hydraulic load cells hydraulicallyconnected to said first plurality of load cells in spaced relation, anda knife edge connected in common to said second plurality of load cellsfor imposing the unbalancing force onto said balance beam.
 3. A scale asset forth in claim 1 further comprising tare spring means secured tosaid beam for restraining the pivoting of said beam, and wherein saidsupport abuts the topside of said balance beam.
 4. A scale as set forthin claim 1 wherein said means for proportionally restraining thepivoting of said balance beam is adjustably mounted at predeterminedpositions longitudinally of said support and said balance beam.
 5. Ascale as set forth in claim 1 wherein said means for proportionallyrestraining the pivoting of said balance beam is a flexure member fixedat one end to said support and at an opposite end to said balance beam.6. A scale as set forth in claim 5 wherein said flexure member ismounted on one side of said support and said means for imposing anunbalancing force is mounted on an opposite side of said support.
 7. Ascale as set forth in claim 1 wherein said means for proportionallyrestraining the pivoting of said balance beam includes at least one rowof coil springs.
 8. A scale as set forth in claim 7 further including atleast one tare spring on an opposite side of said support forrestraining pivoting of said beam, said tare spring functioning in anopposite sense to said coil springs.
 9. A scale as set forth in claim 1wherein said means for measuring a displacement of said balance beamincludes a linear variable differential transformer for sensing thedisplacement of said balance beam and emitting an electrical outputsignal dIrectly proportional to the displacement and a read-out meansconnected to said transformer to receive said output signal and todigitally indicate the weight of the load causing said unbalancing forceon said balance beam in proportional response to said output signal. 10.A scale as set forth in claim 9 wherein said read-out means is a digitalread out.
 11. A scale as set forth in claim 9 wherein said read-outmeans is a DC amp meter calibrated to directly read-out the weight ofthe load.
 12. A scale as set forth in claim 9 wherein said read-outmeans includes a volt meter connected to said transformer to receivesaid output signal and to indicate the voltage strength and direction ofsaid output signal.
 13. A scale as set forth in claim 12 wherein saidread-out means further includes a first precision digital potentiometerconnected to said transformer for adjusting said meter to a zeroequilibrium position corresponding to the balanced position of saidbalance beam whereby said meter can be tared out before an unbalancingforce is applied to said balance beam.
 14. A scale as set forth in claim13 which further includes a second digital volt meter connected to saidtransformer to receive said output signal and a second read-out meansconnected to said second digital volt meter to receive a signaltherefrom; said second volt meter being adjustable to tare out a firstoutput signal whereby subsequent output signals from said transformerare transmitted to said second read-out means to provide measured valuesof net weight of a variable unbalancing force.
 15. A hydraulic scale asset forth in claim 13 wherein said read-out means further includes asecond precision digital pot connected to said transformer and saidmeter for adjusting said meter to said zero equilibrium position withsaid balance beam displaced from said balance position whereby saidmeter can be tared out with said second pot indicating the weight of theload.
 16. A hydraulic scale comprising a load platform for receiving abody to be weighed thereon; a balance beam; a support pivotally mountingsaid balance beam thereon in a balanced position; hydraulic means fortransmitting a force proportional to the weight of a body on said loadplatform to said balance beam to pivotally displace said balance beamfrom said balanced position; first means for proportionally restrainingthe displacement of said balance beam from said position; second meansfor measuring a displacement of said balance beam from said position;and read-out means connected to said second means for indicating aweight proportional to a measured displacement of said balance beamwhereby the weight of the body on said load platform is indicated.
 17. Ahydraulic scale as set forth in claim 16 wherein said load platform isspaced from said balance beam and said support.
 18. A hydraulic scale asset forth in claim 16 wherein said first means is a flexure member. 19.A hydraulic scale as set forth in claim 16 further comprising a tarespring means connected between said support and said beam to restrainpivoting thereof.
 20. A hydraulic scale as set forth in claim 19 whereinsaid support abuts said beam on the topside between said tare springmeans and said first means.
 21. A hydraulic scale comprising a loadplatform for receiving a body to be weighed thereon; a memberhydraulically connected to said load platform for displacement from apredetermined position in response to the placement of a body on saidload platform and movement of said load platform; first means forproportionally restraining displacement of said member from said firstposition; second means for measuring a displacement of said member fromsaid first position; and read-out means connected to said second meansfor indicating a weight proportional to a measured displacement of saidmember whereby the weight of the body on said load platform isindicated.
 22. A hydraulic scale as set forth in claim 21 wherein saidmember is a pivotally mounted balance beam.
 23. A hydraulic scale as setforth in claim 21 further comprising a tare spring means connectedbetween said load platform and said member for restraining movement ofsaid member.
 24. A hydraulic scale as set forth in claim 21 wherein saidfirst means includes a flexure member secured at one end to said balancebeam and at an opposite end to a fixedly mounted support.
 25. Ahydraulic scale as set forth in claim 24 wherein said flexure member isadjustably mounted longitudinally of said balance beam.
 26. A hydraulicscale comprising a load platform for rceiving a body to be weighedthereon; a balance beam; a support pivotally mounting said balance beamthereon in a balanced position; hydraulic means for transmitting a forceproportional to the weight of a body on said load platform to saidbalance beam to pivotally displace said balance beam from said balancedposition; first means for proportionally restraining the displacement ofsaid balance beam from said position; an electrical means spaced fromsaid first means for measuring a displacement of said balance beam fromsaid position; and read-out means connected to said electrical means forindicating a weight proportional to a measured displacement of saidbalance beam whereby the weight of the body on said load platform isindicated.
 27. A hydraulic scale as set forth in claim 26 wherein saidelectrical means is calibrated with respect to said first means.
 28. Ahydraulic scale as set forth in claim 26 wherein said first means is aflexure member and wherein said flexure member and said electrical meansare calibrated with respect to each other whereby the elongation of saidflexure member under load is calibrated with respect to the measuredamount of deflection for a given position of said flexure memberrelative to a fulcrum of said balance beam.
 29. A scale comprising abalance beam; a support pivotally mounting said balance beam thereon ina first position; means for imposing an unbalancing force on saidbalance beam proportional to a load to be weighed for pivoting saidbalance beam on said support from said first position; first means forproportionally restraining the pivoting of said balance beam under animposed unbalancing force; means spaced from said first means formeasuring a displacement of said balance beam from said first positionas a measure of the unbalancing force on said balance beam; and tarespring means secured to said beam for restraining the pivoting of saidbeam, and wherein said support abuts the topside of said balance beam.30. A scale comprising a balance beam; a support pivotally mounting saidbalance beam thereon in a first position; means for imposing anunbalancing force on said balance beam proportional to a load to beweighed for pivoting said balance beam on said support from said firstposition; first means for proportionally restraining the pivoting ofsaid balance beam under an imposed unbalancing force; and means spacedfrom said first means for measuring a displacement of said balance beamfrom said first position as a measure of the unbalancing force on saidbalance beam, said means for measuring a displacement of said balancebeam including a linear variable differential transformer for sensingthe displacement of said balance beam and emitting an electrical out-putsignal directly proportional to the displacement and a readout meansconnected to said transformer to receive said output signal and todigitally indicate the weight of the load causing said unbalancing forceon said balance beam in proportional response to said output signal. 31.A hydraulic scale comprising a load platform for receiving a body to beweighed thereon; a balance beam; a support pivotally mounting saidbalance beam thereon in a balanced position and abutting said beam onthe toPside thereof; hydraulic means for transmitting a forceproportional to the weight of a body on said load platform to saidbalance beam to pivotally displace said balance beam from said balancedposition; first means on one side of said support for proportionallyrestraining the displacement of said balance beam from said position;second means spaced from said first means for measuring a displacementof said balance beam from said balanced position; read-out meansconnected to said second means for indicating a weight proportional to ameasured displacement of said balance beam whereby the weight of thebody on said load platform is indicated; and a tare spring meansconnected between said support and said beam on an opposite side of saidsupport from said first means to restrain pivoting of said beam.
 32. Ahydraulic scale comprising a load platform for receiving a body to beweighed thereon; a member hydraulically connected to said load platformfor displacement from a predetermined position in response to theplacement of a body on said load platform and movement of said loadplatform; first means for proportionally restraining displacement ofsaid member from said position, said first means including a pneumaticsystem for impinging a jet of air on said member, the force of said jetair being proportional to the displacement of said member; second meansfor measuring a displacement of said member from said position; andread-out means connected to said second means for indicating a weightproportional to a measured displacement of said member whereby theweight of the body on said load platform is indicated.